The end of rollers in such a bearing normally consist of a chamfered section. There is normally a relatively sharp edge between the chamfered section and the rest of the roller. At roller bearings of this type with symmetrical, barrel shaped rollers and especially when used on a substantially vertical axis, as shown in FIG. 1, a roller in the unloaded zone might move outwards to an extent permitted by the internal radial clearance. The relatively sharp edge between the chamfered section and the rest of the roller is thus in contact with the raceways. As the rotation continues the roller is forced to regain its normal position, i.e. it is caused to move towards the centre. This causes problems relating to stresses, service life and lubricant film thickness. These problems can be solved in the way that the relatively sharp edge between the chamfered section and the rest of the roller is rounded according to certain criteria.
SE-C 8404813-1 shows a bearing of the type where rollers and race tracks have longitudinal section profiles with substantially the same radius of curvature and which radius is bigger than the distance between the outer race track and the axis of the bearing, measured perpendicularly to the race track, whereby the rollers during normal operating conditions are axially moveable between the race tracks without hindrance from axial confinements at the race tracks for allowing relative misalignment and axial displaceability of the race tracks. Such a bearing is especially susceptible to the problems referred to hereabove.
U.S. Pat. No. 4,802,775, discloses a roller bearing having rollers with rounded end portions. It comprises an inner race, an outer race and rollers arranged between these races. The roller has a predetermined relationship between a maximum diameter of each roller, length of each roller, and radius of curvature of a contact portion between a rolling surface of the roller and a chamfer portion of the roller. The predetermined relationship is presented below. EQU 0.04(Dalr).ltoreq.Rk.ltoreq.0.20(Dalr), where
Rk, Da and lr denotes curvature radius, maximum diameter of the roller and length of the roller, respectively. In this bearing there will be a radius of curvature which is not big enough for ascertaining that the stresses will be so small that the problems mentioned above are avoided.